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Car Forum / Volkswagen / Water Cooled Volkswagen Cars / February 200778 VW Rabbit Diesel New Cylinder Head Leaks Oil In Coolant
I replaced the cylinder head, cylinder head bolts, timing belt, tensioner, and head gasket on my 78 VW Rabbit Diesel. It runs great, but now leaks a small quantity of oil into the coolant. I then replaced the head gasket (again), and applied the torque settings to the bolts as outlined in the Bentley manual, but it still leaks. I did not have this problem prior to the head replacement. The cylinder head is under warranty--my initial assumption is that there is a problem with this rebuilt head. Could anyone help me out with some advice on how I should proceed? Thank you in advance! Jeff > I replaced the cylinder head, cylinder head bolts, timing belt, > tensioner, and head gasket on my 78 VW Rabbit Diesel. It runs great, [quoted text clipped - 11 lines] > > Jeff Did you check the Head & Block for flatness? Most heads are lapped for flatness to prevent exactly what you are suggesting. And if your block has not been checked, it too could be out-of-flat. If you have access to a machinist's rule and some gauging tape, you might be able to determine (crudely) if your block is OK. Next: Did you use (or does VW suggest) an oversized headgasket? Sometimes if the head is milled flat, such is required for proper piston clearance. Whoever sold you the head should address that directly. Next: Are there any cracks in the head or block? You can get a kit to detect cracks (I believe from VersaChem). Check the head while you are at it, especially if it was rebuilt and not *brand* new... and even then. Next: Last time I did a head, there were also some small O-rings that needed to go in with the head at some oil channels and so forth. Does the Rabbit have those? If it is an "old" rabbit, it just might. Did you perhaps forget one of those? Next, and please do not take this the wrong way: It makes a difference as to how the head-bolts are sequenced and torqued, and the degree to which they are tightened on each pass. I am sure you got this correct... just asking. Can you see where the oil is getting through the gasket? There should be some sort of mark or stain or some such indicating the leak point. Last: Are you getting an audible *POP* when cold if you were to remove the radiator cap? Good luck with it. Peter Wieck Wyncote, PA did you clean out al the block head bolt holes? If not you may have cracked the block between the oil pressure feed and the head bolt near it. It was common on the early blocks to crack there even before the engine was taken apart. >I replaced the cylinder head, cylinder head bolts, timing belt, > tensioner, and head gasket on my 78 VW Rabbit Diesel. It runs great, [quoted text clipped - 11 lines] > > Jeff You cannot use an oversized gasket on a VW diesel. The thickness is selected based on piston height above the block surface to maintain valve piston clearance and proper compression. Unfortunately This problem will not be easy to find. He could be leaking anywhere, the head could be cracked, or warped. the block bolt holes for the head could be cracked. It could be anywhere. Even unrelated to the head change. He doesn't say how much its leaking either. Or what shape the car is in. This could help decide how to make a repair or find the leak. > did you clean out al the block head bolt holes? If not you may have > cracked the block between the oil pressure feed and the head bolt near it. [quoted text clipped - 16 lines] >> >> Jeff BTDT. As far as headgasket thickness you are correct. But did I ever tell you about my 81 Hi-performance Dasher diesel? Among us techs it was a well know fact that the early diesel had problems starting in cold weather. I purchased a diesel for almost nothing because it needed a head due to warping. I fixed it by having a machine shop "true" the head on a CNC machine and installed a 1-notch headgasket vs the 2 or 3 it required. Also lowered the RPM limiter some. The result was an diesel that would run like a.... well hi-po diesel. It had so much compression it would cold start without pre-glowing the plugs. Ran it for 2 years then sold it to my friend who ran it into the ground. > You cannot use an oversized gasket on a VW diesel. The thickness is > selected based on piston height above the block surface to maintain valve [quoted text clipped - 24 lines] >>> >>> Jeff Did you use the stock cyl head bolts in the '81 Dasher, or did you install some racing studs and nuts? I have had early Rabbit diesels ('78 and '80) and thought they were waaaay tooooo slow. Then when I purchased an '84 Rabbit Diesel it was almost as fast as a gas Rabbit. Purchased in 1986 with 250K miles on it for only $2K US from a dealership. They wanted it gone and I wanted it! WIN-WIN! Well it was not really as fast as the gas Rabbits, but it was much better than the '78 Rabbit Diesel in starting and acceleration. There is a Quantum turbo diesel around me that is selling cheap. Floor is rusted out and the engine now has a dead cylinder. I would need it to be given to me so I can do something with the TD engine. The owners think that it is still worth thousands. lol I think I have seen one cracked block cause the oil and coolant to mix on an early diesel. Usually I find that the cylinder head needs attention and of course new head gasket and new bolts. ;-) I vote for a bad gasket! I think I have seen that little oval shaped seal become deformed on some of the head gaskets too. later, dave (One out of many daves) > BTDT. As far as headgasket thickness you are correct. But did I ever tell > you about my 81 Hi-performance Dasher diesel? Among us techs it was a well [quoted text clipped - 6 lines] > without pre-glowing the plugs. Ran it for 2 years then sold it to my > friend who ran it into the ground. I think he said he changed the gasket twice already. I,m assuming its not the gasket because of that. And he says it runs fine. I'm not assuming anything else. It could be a cracked block bolt hole. Or a warped head. Or a cracked head. That would be my next choice if I couldn't figure anything without disassembly. I would like to know how much oil is leaking in the antifreeze. And who rebuilt the head and to what standards. > Did you use the stock cyl head bolts in the '81 Dasher, or did you install > some racing studs and nuts? [quoted text clipped - 31 lines] >> cold start without pre-glowing the plugs. Ran it for 2 years then sold it >> to my friend who ran it into the ground. I am with you! Lets check out that rebuilt head! But if the gasket is installed the same way twice and it was wrong or incomplete. Could it even be the wrong gaskets? Like gaskets for the gas engine maybe? Any sealing compound applied on the gasket? I think someone mentioned that there is a small gasket/ring/seal that is inserted inside of the head gasket to seal one the oil feeding the upper cylinder head. http://www.theautochannel.com/autoparts/generalbestvolkswagen/itemz1899_63143tvi.html I want to say that I have seen that oval shaped copper ring loose on some diesel head gaskets, but it has been waaaay too long since I have taken a diesel engine apart. Without that ring installed it may cause the problem the OP is having. ;-) If you note the application on this website it states that it fits the 75-84 Rabbit Diesel. AFAIK The engine changed in 1981 and so did the cyl head gasket. So it is possible the gasket could be the wrong one. Grasping at straws now! <g> So the block needs to be throughly checked. The head needs to be pressure tested or other means of checking for damage. Now why was the original head taken off the first time? Same problem? Was this "rebuilt" head properly serviced? And by whom? Can the original head be serviced and reinstalled? I would suspect this "rebuilt" head since he did not have this problem until this head was installed. So the only variables are a different head and a different gasket. I will ASSuME that the installation was correct! BTW I had a head gasket on my '91 Passat 16V that was allowing oil into my cooling system. I have not seen this problem on any of the diesels yet. ;-) >I think he said he changed the gasket twice already. I,m assuming its not >the gasket because of that. And he says it runs fine. I'm not assuming >anything else. It could be a cracked block bolt hole. Or a warped head. Or >a cracked head. That would be my next choice if I couldn't figure anything >without disassembly. I would like to know how much oil is leaking in the >antifreeze. And who rebuilt the head and to what standards. machine shop friend made up some titanium head bolts! Never had a leakage issue. > Did you use the stock cyl head bolts in the '81 Dasher, or did you install > some racing studs and nuts? [quoted text clipped - 31 lines] >> cold start without pre-glowing the plugs. Ran it for 2 years then sold it >> to my friend who ran it into the ground. Those bolts must have cost as much as the Dasher! 8^) I had a feeling that you might have gone with stronger bolts/studs like from Raceware. I guess if I get another diesel or build a high performance engine (turbo or super charged), I will need some better than stock bolts to keep things together. <g> > machine shop friend made up some titanium head bolts! Never had a leakage > issue. [quoted text clipped - 35 lines] >>> it would cold start without pre-glowing the plugs. Ran it for 2 years >>> then sold it to my friend who ran it into the ground. that's why VW went to larger diameter head bolts somewhere around 1982 or so. > Those bolts must have cost as much as the Dasher! 8^) > I had a feeling that you might have gone with stronger bolts/studs like [quoted text clipped - 43 lines] >>>> compression it would cold start without pre-glowing the plugs. Ran it >>>> for 2 years then sold it to my friend who ran it into the ground. > BTDT. As far as headgasket thickness you are correct. But did I ever tell > you about my 81 Hi-performance Dasher diesel? Among us techs it was a well [quoted text clipped - 39 lines] >>>>Unfortunately I was never into moding diesels, Just making them run >>>>right ,forever. Although they are capable of taking it. the only thing good was the price of a few $100. Other than that it was all wrong. 4doors, beige outside and dark brown inside. But with 500psi of compression it would run 4th gear to the limiter. >> BTDT. As far as headgasket thickness you are correct. But did I ever tell >> you about my 81 Hi-performance Dasher diesel? Among us techs it was a [quoted text clipped - 39 lines] >>>>>Unfortunately I was never into moding diesels, Just making them run >>>>>right ,forever. Although they are capable of taking it. |
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